What can I do about this guy?

Well there is this guy that is in some of my classes, we are kind of friends, but not really. Well every time on online (on AIM or Myspace) he ALWAYS talks to me. I really just feel like saying to him, "Do you have any other friends you can chat with, because you are very annoying!" And sometimes I purposely try to ignore him by not saying hi back, but then he keeps saying "hey" like every 2 mins. We have one really crazy teacher that we always used to talk about a few months ago, and now when we get out of his class, he'll always wait outside the classroom for me. Do you think he likes me? Because I don't like him, and already have another guy that likes me, and I like him! What should I do?!?!